(a) Field of the Invention
The present invention relates to a seat cushion extension apparatus and, more particularly, to a seat cushion extension apparatus in which the front-back length of a seat cushion can be freely extended, and limitations in the thickness of a cushion pad or the like are removed.
(b) Description of the Related Art
In general, a seat provided in a vehicle includes a seat cushion which supports the buttocks of an occupant seated thereon so that the occupant feels comfortable, a seatback which supports the back of the occupant, and a headrest which supports the head and neck of the occupant.
In such a conventional vehicle seat, the seat cushion has a preset size, which is not adjustable. Therefore, the seat cushion is somewhat inadequate to provide optimum comfort to occupants having a variety of physical sizes.
For example, when the occupant has long legs, the conventional seat cushion fails to sufficiently support the thighs of the occupant. This may be inconvenient to the occupant, and the occupant may complain about this.
Therefore, a seat cushion extension apparatus was proposed in order to satisfy this need. The seat cushion extension apparatus has an operation mechanism which pushes a part of the seat cushion so that the part of the seat cushion protrudes forward.
An example of such a seat cushion extension apparatus was disclosed in Korean Laid-Open Patent Publication No. 10-2011-0031782 (Mar. 29, 2011). FIGS. 1 to 3 illustrate the configuration and operation of the seat cushion extension apparatus disclosed in this related art document.
Referring to FIGS. 1 to 3 (RELATED ART), reference numeral 1 indicates a cushion frame that forms the framework of a seat cushion, and reference numeral 30 indicates an extension plate. When an extension motor (not shown) operates, the extension plate 30 protrudes and deploys from the cushion frame 1 while rotating upwards.
The extension plate 30 is connected to a gear unit 20 which converts the rotational force of the extension motor into a linear motion force, and cooperates with the operation of the gear unit 20. The extension plate 30 is supported by a support rod 31 on the cushion frame 1 such that it can produce a sufficient amount of supporting force when a body part (e.g. thighs) of the occupant is placed thereon.
Opposite ends of the support rod 31 are coupled with rotary links 32, which are rotatably coupled with front portions of the cushion frame 1.
In addition, the support rod 31 is coupled with the extension plate 30 such that it can support the entire extension plate 30 along the lengthwise direction.
Furthermore, the gear unit 20 includes a lead screw 23, the front end of which is hinge-coupled with the extension plate 30, and gears (not shown) which convert the rotational force of the extension motor into the linear motion force to linearly displace the lead screw 23 forward and backward.
In FIGS. 1 to 3, reference numeral 24 indicates a gear box which is fixed to the bottom surface of the cushion frame 1 via a mounting bracket 24a, and through which the lead screw 23 extends. The gears which convert the rotational force of the extension motor into the linear motion force of the lead screw 23 are disposed inside the gear box 24.
FIG. 2 shows a position in which the lead screw 23 has moved to the rearmost position. In this position, the extension plate 30 coupled with the lead screw 23 is lowered to a position close to the cushion frame 1.
In this state, when the occupant operates the extension motor by manipulating a switch, the driving force of the extension motor moves the lead screw 23 forward. Consequently, the extension plate 30 coupled with the lead screw 23 rises while rotating, and protrudes and deploys forward of the cushion frame 10, as shown in FIG. 3.
At this time, since the rotary links 32 coupled with the extension plate 30 via the support rod 31 rotate on the cushion frame 1, the extension plate 30 can smoothly rotate and rise.
As described above, the seat cushion extension apparatus is the apparatus which allows the occupant to extend the front part of the seat cushion depending on his/her physical attributes such that the seat cushion can sufficiently support his/her thighs. In the related art, the seat cushion extension apparatus has an operation mechanism that concurrently rotates and raises the extension plate in order to support the thighs.
However, in the conventional seat cushion extension apparatus, the hinge point of the rotary link serving as the center of rotation of the extension plate is positioned above the cushion frame. Consequently, the extension plate deploys about the hinge point that is positioned above, thereby limiting the thickness of the cushion pad which is designed to provide convenience and comfort when the occupant is seated on the seat cushion.
In addition, the extension plate is configured such that it deploys while rotating upwards, thereby limiting the front-back length of the seat cushion part that can be extended.
The information disclosed in the Background of the Invention section is only for the enhancement of understanding of the background of the invention, and should not be taken as an acknowledgment or any form of suggestion that this information forms a prior art that would already be known to a person skilled in the art.